Recently identified lipids have been shown to exhibit phagocyte modulating effects that have formerly been attributed only to peptides. The proposed research is designed to answer several basic questions regarding the effects of lipids on phagocyte functions including chemotaxis, phagocytosis, locomotion, and lysosomal enzyme release. The endogenous chemotactic lipid, HETE (12L-OH, 5,8,10,14-eicosatetraenoic acid) will be used as a prototype in studies of structure vs function. Analogs and sub-analogs of HETE will be synthesized chemically and enzymatically in order to determine the minimum structural requirements for chemotactic function. Radioactively labeled compounds will be incubated with phagocytes (neutrophils, monocytes, and alveolar macrophages) to obtain autoradiograms of lipid-cell interaction. Metabolism of lipid modulators will be monitored by recovering lipid breakdown products from lipid-cell incubations. Product identification will be made using thin layer chromatography, spectrophotometry, high pressure liquid chromatography, and mass spectrometry. Chemotaxis and locomotion will be assayed using Zigmond's checkerboard analysis of the leading front technique, Boyden's classical micropore filter method, and Nelson's migration assay under agarose gels. When considered in light of the current knowledge of peptide-mediated phagocyte responses, information gained from this project should allow a broader perspective for rationalizing the mechanisms by which phagocytes perform their host defense functions.